Tapes and labels including a layer of a normally tacky, pressure-sensitive adhesive adhered to at least one surface of a supporting web are typically sheared to size during one or more operations in their manufacture. Shearing of a plurality of layers of such tapes and labels typically is carried out by using a knife blade. This operation is known in the art as guillotining.
During a guillotining or other similar shearing step, the pressure-sensitive adhesive has the tendency to flow either because of its general liquidity, or as a combination of that general liquidity and the exertion of pressure exerted by the knife blade alone or in conjunction with that exerted by a means for holding a plurality of tapes or labels during this shearing operation. As a result of the adhesive flow during a guillotine operation, the knife blade tends to become coated with a layer of adhesive. That coating tends to reduce the efficacy of further shearing cuts and also can deposit and smear adhesive on the edge surfaces of the articles being cut.
U.S. Pat. No. 4,346,189 disclose the use of a polysiloxane additive in solvent-based normally tacky, pressure-sensitive adhesives to reduce the flow at cut edges in the preparation of adhesive tapes and labels containing pressure-sensitive adhesives. While the use of polysiloxanes to reduce the build-up of adhesive on the knife blade and reduce flow of the adhesive during guillotining operations provides some benefit, the polysiloxane materials disclosed in U.S. Pat. No. 4,346,189 are relatively costly.
Polyoxyalkylene polyols such as polyethylene glycol have been used in adhesive compositions at various concentrations and in average molecular weights which range from about 200 to about 20,000. U.S. Pat. No. 3,096,202 describes the use of a polyethylene glycol present at about 15 to about 100 percent of the weight of a partially cross-linked elastomeric polyvinyl pyrrolidone polymer in the formation of a water-soluble but normally tacky, pressure-sensitive adhesive. U.S. Pat. No. 3,540,580 teaches water-based, thermoplastic heat sealing adhesives made from a polyvinyl acetate emulsion which may contain a polypropylene glycol or other ingredient as an antipenetrant to decrease the wetting properties of the formed adhesive. U.S. Pat. No. 4,068,033 discloses an adhesive composition that becomes tacky when heated and may contain a polyethylene glycol as a tackifying ingredient. U.S. Pat. No. 4,129,359 discloses a repulpable hot melt adhesive based upon vinyl copolymers in which polyethylene glycols having molecular weights of about 10,000 to about 20,000 are utilized to assist in water solubility of the ultimate adhesive while polyethylene glycols of a molecular weight of about 200 to about 1,000 are utilized as plasticizing agents. U.S. Pat. No. 4,325,851 discloses water activated hot melt-applied adhesives that can use a polyethylene glycol wax having a molecular weight of about 4,000 to about 20,000 to assist in retarding of blocking of adhesive-coated sheets. However, none of the above art teaches or suggests the present invention.